1. Field of the Invention
This invention relates to pipe swivel joints, and more particularly to such swivel joints with multiple flow passageways for the simultaneous transfer of a plurality of separate fluids.
2. Description of the Prior Art
The production of oil and gas from offshore wells has developed into a major endeavor of the petroleum industry, and this growth has led to the development of various means for transporting petroleum and its products from offshore locations to shore-based refineries or storage facilities. Many of these wells now are being drilled and completed in deep water where the use of marine tankers of very large capacity constitutes the most practical and efficient transportation method.
One of the more common facilities employed in such a tanker operation is an offshore floating terminal comprising an arrangement of hoses, pipes and/or other fluid conduits supported on a buoy to which the tanker is moored during loading/unloading. The tanker and the buoy move relative to each other in response to the influence of wind, tide, water currents and the loading or unloading of cargo or fuel, thus requiring a flexible hose or articulated pipe with swivel joints between the tanker and the buoy. As the loading/unloading operation frequently involves more than one type of fluid, for example, crude oil, kerosene, and bunker fuel, and sometimes large volumes of vapor generated during the transfer operation must be conducted to a storage or recovery facility, the several fluids are loaded or unloaded, either one at a time through a single conduit or simultaneously through a plurality of conduits all of which are connected to a single, multiple-conduit coaxial swivel joint on the buoy. This type of swivel joint has two or more interconnected chambers each communicating with an inlet and a corresponding outlet to provide two or more separate and distinct flow paths, and although such devices provide the desired function they are relatively complex and thus difficult and expensive both to manufacture and to service.
What is needed, therefore, is a coaxial swivel joint that has a plurality of separate and distinct fluid flow passages between a plurality of inlets and a plurality of outlets, that is relatively uncomplex in design and thus inexpensive to manufacture, and that is easy to clean and maintain.